the Ka for acetic acid, HC2H3O2, is 1.8x10-5 at 25 deg. Celsius. In a .10 M solution of potassium acetate, which of the following are true?

I. [HC2H3O2] = [OH-]
II. [H+] = [OH-]
III. [C2H3O2-] < .10 M

a. I only
b. II only
c. III only
d. I and II
e. I, II and III

What is your thinking on this? Ask yourself why would I be true, or II, or III?

We will be happy to critique your thinking.

To determine which statements are true in a 0.10 M solution of potassium acetate, we need to consider the dissociation of acetic acid and the acetate ion in water.

The dissociation equation for acetic acid in water is:

HC2H3O2 ⇌ H+ + C2H3O2-

1. Statement I: [HC2H3O2] = [OH-]

This statement is not true because acetic acid is a weak acid, so it only dissociates partially in water. As a result, [HC2H3O2] will not be equal to [OH-], which comes from the dissociation of water.

2. Statement II: [H+] = [OH-]

This statement is not true because acetic acid is a weak acid, and its dissociation does not produce equal concentrations of H+ and OH- ions. In a weak acid solution, the concentration of H+ ions will be less than the concentration of OH- ions.

3. Statement III: [C2H3O2-] < 0.10 M

This statement is true because potassium acetate fully dissociates in water to produce cations and anions. The concentration of C2H3O2- ions will be equal to the initial concentration of potassium acetate, which is 0.10 M.

Based on this analysis, none of the statements (I, II, or III) is true. So, the correct answer is (e) None of the statements are true.

To determine which of the statements are true, we need to understand the dissociation of acetic acid and potassium acetate in water.

Acetic acid, HC2H3O2, is a weak acid that partially dissociates in water:
HC2H3O2 ⇌ H+ + C2H3O2-

Potassium acetate, on the other hand, is a strong electrolyte and fully dissociates in water:
KCH3CO2 ⇌ K+ + CH3CO2-

Now, let's evaluate each statement individually:

I. [HC2H3O2] = [OH-]
This statement suggests that the concentration of the acetic acid is equal to the concentration of hydroxide ions. Since acetic acid is a weak acid, it only partially dissociates to contribute to the hydrogen ion concentration. However, hydroxide ions are produced from the dissociation of water. In a neutral solution, the concentration of hydroxide ions ([OH-]) is equal to the concentration of hydrogen ions ([H+]). Hence, this statement is not true.

II. [H+] = [OH-]
This statement implies that the concentration of hydrogen ions is equal to the concentration of hydroxide ions. In a neutral solution, the concentration of hydrogen ions ([H+]) is equal to the concentration of hydroxide ions ([OH-]). Since statement I is false and acetic acid is a weak acid, there will be a presence of hydrogen ions that will contribute to the acidity of the solution. Therefore, this statement is also not true.

III. [C2H3O2-] < 0.10 M
This statement suggests that the concentration of acetate ions is less than 0.10 M. In a 0.10 M solution of potassium acetate, all of the potassium acetate will fully dissociate, resulting in a concentration of acetate ions equal to 0.10 M. Therefore, this statement is false.

Based on our analysis, none of the given statements are true. The correct answer would be (e) None of the statements are true.

Ka = [H+]

pH= -log[1.8x10^-5]
pH = 5

I dont understand